mirror of
https://github.com/tinygo-org/drivers.git
synced 2026-07-26 10:38:41 +00:00
Austen LeBeau
GitHub
@@ -31,6 +31,8 @@ smoke-test:
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@md5sum ./build/test.hex
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tinygo build -size short -o ./build/test.hex -target=itsybitsy-m0 ./examples/bmp280/main.go
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@md5sum ./build/test.hex
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tinygo build -size short -o ./build/test.hex -target=trinket-m0 ./examples/bmp388/main.go
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@md5sum ./build/test.hex
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tinygo build -size short -o ./build/test.hex -target=bluepill ./examples/ds1307/sram/main.go
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@md5sum ./build/test.hex
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tinygo build -size short -o ./build/test.hex -target=bluepill ./examples/ds1307/time/main.go
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@@ -0,0 +1,249 @@
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package bmp388
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import (
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"errors"
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"tinygo.org/x/drivers"
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)
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var (
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errConfigWrite = errors.New("bmp388: failed to configure sensor, check connection")
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errConfig = errors.New("bmp388: there is a problem with the configuration, try reducing ODR")
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errCaliRead = errors.New("bmp388: failed to read calibration coefficient register")
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errSoftReset = errors.New("bmp388: failed to perform a soft reset")
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errNotConnected = errors.New("bmp388: not connected")
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)
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type Oversampling byte
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type Mode byte
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type OutputDataRate byte
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type FilterCoefficient byte
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// Config contains settings for filtering, sampling, and modes of operation
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type Config struct {
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Pressure Oversampling
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Temperature Oversampling
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Mode Mode
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ODR OutputDataRate
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IIR FilterCoefficient
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}
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// Device wraps the I2C connection and configuration values for the BMP388
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type Device struct {
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bus drivers.I2C
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Address uint8
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cali calibrationCoefficients
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Config Config
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}
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type calibrationCoefficients struct {
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// Temperature compensation
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t1 uint16
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t2 uint16
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t3 int8
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// Pressure compensation
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p1 int16
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p2 int16
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p3 int8
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p4 int8
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p5 uint16
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p6 uint16
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p7 int8
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p8 int8
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p9 int16
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p10 int8
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p11 int8
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}
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// New returns a bmp388 struct with the default I2C address. Configure must also be called after instanting
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func New(bus drivers.I2C) Device {
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return Device{
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bus: bus,
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Address: Address,
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}
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}
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// Configure can enable settings on the BMP388 and reads the calibration coefficients
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func (d *Device) Configure(config Config) (err error) {
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d.Config = config
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if d.Config == (Config{}) {
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d.Config.Mode = Normal
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}
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// Turning on the pressure and temperature sensors and setting the measurement mode
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err = d.writeRegister(RegPwrCtrl, PwrPress|PwrTemp|byte(d.Config.Mode))
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// Configure the oversampling, output data rate, and iir filter coefficient settings
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err = d.writeRegister(RegOSR, byte(d.Config.Pressure|d.Config.Temperature<<3))
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err = d.writeRegister(RegODR, byte(d.Config.ODR))
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err = d.writeRegister(RegIIR, byte(d.Config.IIR<<1))
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if err != nil {
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return errConfigWrite
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}
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// Check if there is a problem with the given configuration
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if d.configurationError() {
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return errConfig
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}
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// Reading the builtin calibration coefficients and parsing them per the datasheet. The compensation formula given
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// in the datasheet is implemented in floating point
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buffer, err := d.readRegister(RegCali, 21)
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if err != nil {
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return errCaliRead
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}
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d.cali.t1 = uint16(buffer[1])<<8 | uint16(buffer[0])
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d.cali.t2 = uint16(buffer[3])<<8 | uint16(buffer[2])
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d.cali.t3 = int8(buffer[4])
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d.cali.p1 = int16(buffer[6])<<8 | int16(buffer[5])
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d.cali.p2 = int16(buffer[8])<<8 | int16(buffer[7])
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d.cali.p3 = int8(buffer[9])
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d.cali.p4 = int8(buffer[10])
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d.cali.p5 = uint16(buffer[12])<<8 | uint16(buffer[11])
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d.cali.p6 = uint16(buffer[14])<<8 | uint16(buffer[13])
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d.cali.p7 = int8(buffer[15])
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d.cali.p8 = int8(buffer[16])
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d.cali.p9 = int16(buffer[18])<<8 | int16(buffer[17])
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d.cali.p10 = int8(buffer[19])
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d.cali.p11 = int8(buffer[20])
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return nil
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}
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// Read the temperature registers and compute a compensation value for the temperature and pressure compensation
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// calculations. This is not the temperature itself.
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func (d *Device) tlinCompensate() (int64, error) {
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rawTemp, err := d.readSensorData(RegTemp)
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if err != nil {
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return 0, err
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}
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// pulled from C driver: https://github.com/BoschSensortec/BMP3-Sensor-API/blob/master/bmp3.c
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partialData1 := rawTemp - (256 * int64(d.cali.t1))
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partialData2 := int64(d.cali.t2) * partialData1
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partialData3 := (partialData1 * partialData1)
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partialData4 := partialData3 * int64(d.cali.t3)
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partialData5 := (partialData2 * 262144) + partialData4
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return partialData5 / 4294967296, nil
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}
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// ReadTemperature returns the temperature in centicelsius, i.e 2426 / 100 = 24.26 C
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func (d *Device) ReadTemperature() (int32, error) {
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tlin, err := d.tlinCompensate()
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if err != nil {
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return 0, err
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}
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temp := (tlin * 25) / 16384
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return int32(temp), nil
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}
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// ReadPressure returns the pressure in centipascals, i.e 10132520 / 100 = 101325.20 Pa
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func (d *Device) ReadPressure() (int32, error) {
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tlin, err := d.tlinCompensate()
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if err != nil {
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return 0, err
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}
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rawPress, err := d.readSensorData(RegPress)
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if err != nil {
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return 0, err
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}
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// code pulled from bmp388 C driver: https://github.com/BoschSensortec/BMP3-Sensor-API/blob/master/bmp3.c
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partialData1 := tlin * tlin
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partialData2 := partialData1 / 64
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partialData3 := (partialData2 * tlin) / 256
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partialData4 := (int64(d.cali.p8) * partialData3) / 32
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partialData5 := (int64(d.cali.p7) * partialData1) * 16
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partialData6 := (int64(d.cali.p6) * tlin) * 4194304
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offset := (int64(d.cali.p5) * 140737488355328) + partialData4 + partialData5 + partialData6
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partialData2 = (int64(d.cali.p4) * partialData3) / 32
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partialData4 = (int64(d.cali.p3) * partialData1) * 4
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partialData5 = (int64(d.cali.p2) - 16384) * tlin * 2097152
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sensitivity := ((int64(d.cali.p1) - 16384) * 70368744177664) + partialData2 + partialData4 + partialData5
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partialData1 = (sensitivity / 16777216) * rawPress
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partialData2 = int64(d.cali.p10) * tlin
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partialData3 = partialData2 + (65536 * int64(d.cali.p9))
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partialData4 = (partialData3 * rawPress) / 8192
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// dividing by 10 followed by multiplying by 10
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// To avoid overflow caused by (pressure * partial_data4)
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partialData5 = (rawPress * (partialData4 / 10)) / 512
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partialData5 = partialData5 * 10
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partialData6 = (int64)(uint64(rawPress) * uint64(rawPress))
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partialData2 = (int64(d.cali.p11) * partialData6) / 65536
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partialData3 = (partialData2 * rawPress) / 128
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partialData4 = (offset / 4) + partialData1 + partialData5 + partialData3
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compPress := ((uint64(partialData4) * 25) / uint64(1099511627776))
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return int32(compPress), nil
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}
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// SoftReset commands the BMP388 to reset of all user configuration settings
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func (d *Device) SoftReset() error {
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err := d.writeRegister(RegCmd, SoftReset)
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if err != nil {
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return errSoftReset
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}
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return nil
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}
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// Connected tries to reach the bmp388 and check its chip id register. Returns true if it was able to successfully
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// communicate over i2c and returns the correct value
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func (d *Device) Connected() bool {
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data, err := d.readRegister(RegChipId, 1)
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return err == nil && data[0] == ChipId // returns true if i2c comm was good and response equals 0x50
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}
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// SetMode changes the run mode of the sensor, NORMAL is the one to use for most cases. Use FORCED if you plan to take
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// measurements infrequently and want to conserve power. SLEEP will of course put the sensor to sleep
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func (d *Device) SetMode(mode Mode) error {
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d.Config.Mode = mode
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return d.writeRegister(RegPwrCtrl, PwrPress|PwrTemp|byte(d.Config.Mode))
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}
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func (d *Device) readSensorData(register byte) (data int64, err error) {
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if !d.Connected() {
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return 0, errNotConnected
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}
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// put the sensor back into forced mode to get a reading, the sensor goes back to sleep after taking one read in
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// forced mode
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if d.Config.Mode != Normal {
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err = d.SetMode(Forced)
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if err != nil {
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return
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}
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}
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bytes, err := d.readRegister(register, 3)
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if err != nil {
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return
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}
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data = int64(bytes[2])<<16 | int64(bytes[1])<<8 | int64(bytes[0])
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return
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}
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// configurationError checks the register error for the configuration error bit. The bit is cleared on read by the bmp.
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func (d *Device) configurationError() bool {
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data, err := d.readRegister(RegErr, 1)
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return err == nil && (data[0]&0x04) != 0
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}
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func (d *Device) readRegister(register byte, len int) (data []byte, err error) {
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data = make([]byte, len)
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err = d.bus.ReadRegister(d.Address, register, data)
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return
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}
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func (d *Device) writeRegister(register byte, data byte) error {
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return d.bus.WriteRegister(d.Address, register, []byte{data})
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}
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@@ -0,0 +1,84 @@
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// Package bmp388 provides a driver for Bosch's BMP388 digital temperature & pressure sensor.
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// The datasheet can be found here: https://www.bosch-sensortec.com/media/boschsensortec/downloads/datasheets/bst-bmp388-ds001.pdf
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package bmp388
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const Address byte = 0x77 // default I2C address
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const (
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RegChipId byte = 0x00 // useful for checking the connection
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RegCali byte = 0x31 // pressure & temperature compensation calibration coefficients
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RegPress byte = 0x04 // start of pressure data registers
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RegTemp byte = 0x07 // start of temperature data registers
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RegPwrCtrl byte = 0x1B // measurement mode & pressure/temperature sensor power register
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RegOSR byte = 0x1C // oversampling settings register
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RegODR byte = 0x1D //
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RegCmd byte = 0x7E // miscellaneous command register
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RegStat byte = 0x03 // sensor status register
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RegErr byte = 0x02 // error status register
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RegIIR byte = 0x1F
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)
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const (
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ChipId byte = 0x50 // correct response if reading from chip id register
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PwrPress byte = 0x01 // power on pressure sensor
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PwrTemp byte = 0x02 // power on temperature sensor
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SoftReset byte = 0xB6 // command to reset all user configuration
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DRDYPress byte = 0x20 // for checking if pressure data is ready
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DRDYTemp byte = 0x40 // for checking if pressure data is ready
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)
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// The difference between forced and normal mode is the bmp388 goes to sleep after taking a measurement in forced mode.
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// Set it to forced if you intend to take measurements sporadically and want to save power. The driver will handle
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// waking the sensor up when the sensor is in forced mode.
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const (
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Normal Mode = 0x30
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Forced Mode = 0x16
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Sleep Mode = 0x00
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)
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// Increasing sampling rate increases precision but also the wait time for measurements. The datasheet has a table of
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// suggested values for oversampling, output data rates, and iir filter coefficients by use case.
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const (
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Sampling1X Oversampling = iota
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Sampling2X
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Sampling4X
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Sampling8X
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Sampling16X
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Sampling32X
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)
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// Output data rates in Hz. If increasing the sampling rates you need to decrease the output data rates, else the bmp388
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// will freeze and Configure() will return a configuration error message. In that case keep decreasing the data rate
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// until the bmp is happy
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const (
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Odr200 OutputDataRate = iota
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Odr100
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Odr50
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Odr25
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Odr12p5
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Odr6p25
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Odr3p1
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Odr1p5
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Odr0p78
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Odr0p39
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Odr0p2
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Odr0p1
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Odr0p05
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Odr0p02
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Odr0p01
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Odr0p006
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Odr0p003
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Odr0p0015
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)
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// IIR filter coefficients, higher values means steadier measurements but slower reaction times
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const (
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Coeff0 FilterCoefficient = iota
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Coeff1
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Coeff3
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Coeff7
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Coeff15
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Coeff31
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Coeff63
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Coeff127
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)
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@@ -0,0 +1,53 @@
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package main
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import (
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"machine"
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"strconv"
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"time"
|
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"tinygo.org/x/drivers/bmp388"
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)
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func main() {
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machine.I2C0.Configure(machine.I2CConfig{})
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sensor := bmp388.New(machine.I2C0)
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if !sensor.Connected() {
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println("Uh oh, BMP388 not detected")
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return
|
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}
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|
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// The accuracy of the sensor can be increased, at the cost of a slower output rate. Table 9 in Section 3.5 of the
|
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// datasheet has recommended settings for common use cases. If increasing the sampling rate, the output data rate
|
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// (ODR) will likely have to be decreased. Configure() will return an error if there's a problem with the
|
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// configuration settings - keep decreasing the ODR and cycling the power to the sensor until it is happy.
|
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err := sensor.Configure(bmp388.Config{
|
||||
Pressure: bmp388.Sampling8X,
|
||||
Temperature: bmp388.Sampling2X,
|
||||
ODR: bmp388.Odr25,
|
||||
IIR: bmp388.Coeff0,
|
||||
Mode: bmp388.Normal,
|
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})
|
||||
|
||||
// This is also fine
|
||||
// err := sensor.Configure(bmp388.BMP388Config{})
|
||||
|
||||
if err != nil {
|
||||
println(err)
|
||||
}
|
||||
|
||||
for {
|
||||
temp, err := sensor.ReadTemperature() // returns the temperature in centicelsius
|
||||
press, err := sensor.ReadPressure() // returns the pressure in centipascals
|
||||
|
||||
if err != nil {
|
||||
println(err)
|
||||
} else {
|
||||
println("Temperature: " + strconv.FormatInt(int64(temp), 10) + " cC")
|
||||
println("Pressure: " + strconv.FormatInt(int64(press), 10) + " cPa\n")
|
||||
}
|
||||
|
||||
time.Sleep(time.Second)
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user